Add missing require.
Add missing require.

As of rspec/rspec-support#245, `rspec/support/ruby_features`
relies upon `rspec/support` being loaded first.
xmik/rspec-core,Teino1978-Corp/Teino1978-Corp-rspec-core,xmik/rspec-core,azbshiri/rspec-core,Teino1978-Corp/Teino1978-Corp-rspec-core,azbshiri/rspec-core,rspec/rspec-core,rspec/rspec-core,Teino1978-Corp/Teino1978-Corp-rspec-core,rspec/rspec-core,xmik/rspec-core,azbshiri/rspec-core